HEVC (High Efficiency Video Coding) is an advanced video coding system being developed under the Joint Collaborative Team on Video Coding (JCT-VC) group of video coding experts from ITU-T Study Group. HEVC is block-based hybrid video coding with very flexible block structure. Three block concepts are introduced for HEVC: coding unit (CU), prediction unit (PU), and transform unit (TU). The overall coding structure is characterized by the various sizes of CU, PU and TU in a recursive fashion, where each picture is divided into largest CUs (LCUs), and each LCU consists of 64×64 pixels. Each LCU is then recursively divided into smaller CUs until leaf CUs or smallest CUs are reached. Once the splitting of CU hierarchical tree is done, each leaf CU is subject to further split into prediction units (PUs) according to prediction type and PU partition. For temporal prediction, the PU types consist of SKIP, MERGE, DIRECT and INTER modes. For spatial prediction, the PU type consists of INTRA mode. For each 2N×2N leaf CU, one partition size is selected. When the PredMode (Prediction Mode) is SKIP, MERGE or DIRECT, the only allowed Part Size (Partition Size) is {2N×2N}. When the PredMode is INTER, the allowed Part Size is selected from {2N×2N, 2N×N, N×2N, N×N}. When the PredMode is INTRA, the allowed Part Size is selected from {2N×2N, N×N}.